It is desirable in fluid-handling conduits to ensure that the connectors used have their male and female portions properly coupled together. A faulty connector enables an associated host system to leak fluid. This can be particularly disadvantageous when the system is under pressure and the leaking connector expels the pressurized fluid.
In the quick connector field, where male and female portions of the connectors are held together by friction locking connections, it is important that the male and female portions are properly coupled wherein the male portion is manually insertable within the female portion to establish a fluid connection therebetween while a seal assembly fluidically seals the coupling portions together.
U.S. Pat. No. 4,819,908 to Norkey discloses a quick connector which also includes a one-way shut-off valve in the female portion of the coupling. Such couplings retain fluid in the fluid system associated with the female portion of the coupling until the male and female portions are connected together. Upon connection, the valve is moved to its open position and enables fluid to flow in the fluid system. Such fluid couplings are used, for example, in automotive air conditioning systems where the portion of the fluid system associated with the female part of the coupling is charged or pressurized with coolant.
Such previously known quick connect fluid couplings with shut-off valves typically suffer from a number of shortcomings. The "Achilles' heel" of prior art approaches was invariably found in the design of the check valve seal. Some designs, such as in U.S. Pat. No. 2,327,611 to Schweiwer, provided an effectively functioning check valve but at the cost of requiring extremely complex and expensive machined parts and multiple seal elements. Such designs, although useful in some applications, had multi part housings requiring complex assembly and fabrication which was not found to be cost competitive in high volume automotive type applications. Other designs, such as that in U.S. Pat. No. 4,819,908 to Norkey, employed a single seal for two distinct functions, to sealingly engage the male portion of the coupling in the engaged condition and, alternatively, to sealingly engage the check valve member upon removal of the male portion of the coupling. Although this approach eliminated some of the expense of earlier designs, it was prone to leakage in the check valve mode of operation inasmuch as it relied entirely upon radial compression of the seal. It has been found in practice that, such quick connect fittings, when subjected to repeated manual coupling and decoupling, can radially distort the female portion of the assembly carrying the seal, resulting in leakage. Furthermore, the seal can take a compressive set after a period of time in the couple condition, thereby losing its radial resiliency and compromising subsequent use of the check valve feature.
Other designs such as disclosed in U.S. Pat. No. 4,601,497 to Bartholomew disclosed the use of a separate check valve seal. However, such designs subject the seal to shear forces during assembly and during check valve operation which can subsequently result in leakage. Furthermore, in all the aforementioned prior art approaches, the valve member itself tends to be relatively large and heavy and can be prone to sticking, particularly in designs involving thin walled female portions.